1. Technical Field
The present invention relates to a light-emitting device including light-emitting elements as organic light-emitting diodes (OLEDs) and an electronic apparatus including the light-emitting device.
2. Related Art
An OLED has a configuration in which a solid light-emitting layer formed of an organic electroluminescence (EL) material is interposed between a cathode and an anode. As the light-emitting device including the OLED, a light-emitting device in which a plurality of OLEDs are arranged on a substrate as pixels is known. In this light-emitting device, the pixels are sealed and are protected against external air. As one of sealing methods, there is provided a thin-film sealing method of forming a thin film on a substrate to configure a sealing layer by the formed thin film. In this thin film sealing method, the sealing layer may be configured by a single layer as disclosed in JP-A-11-74073 or by a plurality of layers as disclosed in JP-A-2004-95199.
FIG. 11 is a cross-sectional view showing a light-emitting device (single-layer configuration) of the related art. A plurality of pixels are arranged in a central portion (not shown) of a pixel substrate 501. The pixels penetrate through a pixel partition 502 on the pixel substrate 501 and a light-emitting region of the pixels is partitioned in the pixel partition 502. A cathode layer 503 is formed on the pixel substrate 501 so as to cover the pixel partition 502. The cathode layer 503 is a cathode which is common to the plurality of pixels, that is, a common cathode. On the pixel substrate 501, a peripheral layer 504 is formed between the pixel partition 502 and a circumferential end of the pixel substrate 501. On the pixel substrate 501, a sealing layer is formed so as to cover the peripheral layer 504 and the cathode layer 503. The sealing layer is formed of a single-layer thin film. In more detail, the sealing layer is a gas barrier film 505 formed of an inorganic material.
FIG. 12 is a cross-sectional view showing a light-emitting device (plural-layer configuration) of the related art. In this light-emitting device, a peripheral layer is not provided between a pixel partition 502 and a circumferential end of a pixel substrate 501. A sealing layer is formed of a three-layer thin film. In more detail, the sealing layer includes an electrode protective film 506 formed on the pixel substrate 501, an organic buffer layer formed thereon, and a gas barrier film 508 formed thereon. These thin films cover a cathode layer 503. The organic buffer layer 507 is formed of an organic material. The electrode protective film 506 and the gas barrier film 508 are formed of inorganic materials and extend beyond the end of the organic buffer film 507.
The width of a frame of the light-emitting device in which the plurality of pixels are arranged on the substrate is preferably narrow. In particular, when the light-emitting device is used as a display device, the narrow frame is of importance. However, in the above-described light-emitting devices of the related art, the position (P1 of FIG. 11) of the end of the gas barrier film 505 or the position (P2 of FIG. 12) of the end of the organic buffer film 507 significantly varies for each light-emitting device. Accordingly, a wide substrate needs to be used and thus the width of the frame widens.
The position P1 or P2 significantly varies according to a method of forming the sealing layer, in each light-emitting device. Since the sealing layer is formed after forming the pixels, the sealing layer is preferably formed using a method which has a negligible influence on the pixels. For example, if the pixel is an OLED, a deposition method or a coating method is generally used. In particular, the employment of a method which has a negligible influence on the pixels is important when a film having a certain degree of thickness, such as the gas barrier film 505 or the organic buffer film 507, is formed. However, in the employable method, positional precision of the end of the formed layer becomes low. Accordingly, the position P1 or P2 significantly varies for each light-emitting device.